Process of indurating boards of fibrous materials



Patented Mar. 16, 1948 PROCESS OF INDURATING. BOARDS OF FIBROUS MATERIALS Inning Olof Vidar Bergstriim, Stocksund, Gustaf Bristol Heijmer, Enebyberg, and Karl Gustaf Trobeck, Stockholm, Sweden No Drawing. Application November 22, 1944, Se-

rial No. 564,734. In Sweden May 14, 1943 and the like of fibrous materials as Well as oils.

particularly suited as emulsifiers for this and other purposes.

In the production of oil-hardened fibrous articles, such as fibre boards of various kinds, there have heretofore been used drying oils, e. g. China-wood oil (tung oil), perilla oil, oiticica oil and dehydrated castor oil (dienol). These oils, in addition to being expensive, suffer from the drawback that they do not fully penetrate the board when applied in the usual way, for which reason the boards will not become completely hardened throughout.

Oil-hardening of e. g. lwood fibre boards is according to known methods accomplished by immersing the board in a suitable oil of the aforementioned kind which has a temperature of 50- 100" C. for about 5 minutes. After this the board is removed and wiped in some suitable way and laced in a heating chamber and kept at a temperature of 130-150 C. for about 15-25 hours. This oil-hardening treatment lowers the water absorption of the board and imparts a higher mechanical strength to the same, particularly in regard to bending and breaking stresses.

The present invention is based on the use of certain fractions and components obtained from tall oil. Tall oil or "tall acid is the common name for the crude product obtained by acidifying so called sulfate soap (liquid resin or sulfate resin), a well known byproduct from the sulfate pulp process. When this tall oil or tall acid (the latter expression being more correct since the product chiefly consists of resinous and fatty acids) is distilled in vacuum, four main products are obtained namely:

(a) A first run or first drops of distillation, called tall resin oil or tall first oil (sometimes also cokill oil, since its chief use hitherto has been for lubricating the inside of ingot molds, so called cokills) and'consisting to about 50% of unsaponlfiable oil-like matter, so called neutral oil, and for the rest mainly of fatty acids;

(b) A liquid product chiefly consisting of fatty acids, sometimes called tall oil or distilled tall oil; according to modern nomenclature called tall fat acid (Vide: Svensk Papperstidning, 194.2,page 203, English summary) (c) A solid resin-like fraction, earlier called sulfate resin, now called tall resin acid and chiefly consisting of abietic acid; and

(d) A distillation residue called tall pitch,

2 Claims. (Cl. 117149) It has, however, been discovered that another mode of dividing the fractions is particularly valuable for obtaining substances having emulsifying qualities. It is known that tall acid contains phytosterines which possess emulsifying properties. The phytosterines are contained-in the higher boiling fractions of the tall acid. Our work has, however, demonstrated that also the first (low boiling) distillate contains substances with marked emulsifying properties. This distillate consists i. a. of neutral substances and fatty acids. It has .been discovered that both the fatty acids and the neutral oils which are separately obtained from this distillate possess emulsifying properties. The distillate first obtained in the fractionating of the tall oil or tall acid has a considerably stronger emulsifying power than the following tall fat acid fraction (cfr. b above). According to our invention the distillation of the tall acid or its fractional components, e. g. tall first oil (cfr. a above) or tall fat acid is carried out in such a manner that the emulsifying substances are obtained to the greatest possible degree. This is accomplished by collecting a suitable fraction or fractions from the distillate which is received prior to the tall fat acid fraction proper, as well as part of last mentioned fraction, in which fractions the emulsifying agent is present in larger proportions.

According to hitherto used methods of recovering products from tall acid, the first fraction consisting of the tall resin oil or tall first oil (cokill oil; cfr. a above) has been collected separately, after which a tall fat acid fraction has been collected (cfr, b above). This latter fraction is characterized by the fact that it has a low content of neutral substances and a content of resinous acidsnot exceeding 25%.v By our discovery that in the first fractions of the distillate from tall acid" are contained emulsifying agents a new mode of working up tall acid has been devised. The distillation according to our invention is thus carried out in such a manner that the first fraction will not consist of tall resin oil as is now generally the case; the distillation is instead continued and distillate collected in this fraction as long as it contains emulsifying substances to any appreciable degree. After this a tall fat acid fraction is collected.

The quantity of emulsifying fraction varies with the composition of the tall acid and appears to a certain degree to be dependent upon the composition of the wood. The progress of the distillation in regard to the emulsifying prop- 3 erty of the distillate to be collected may be controlled by the following simple test:

To 1000 grams of raw linseed oil are added 100 grams of the oil to be tested. To these are added 200 grams of water. The mixture is emulsified by agitation in a homogenizing apparatus. The emulsion should be stable for about 24 hours in order to comply with the requirements according to the invention in regard to the content of emulsifying substances. The product obtained in this manner has a specific gravity below 0.920 and a refractive index of less than 1.480 at 20 C.

We have discovered that these emulsifying oils have a higher faculty of penetration into fibrous materials, e. g. into wood fibre boards, than the heretofore employed oils, whereby a considerably better effect in regard to complete hardening throughout the board has been obtained.

It is not necessary to use these new oils separately as in many cases they may to great advantage be combined with such oils as are at present used for the hardening purpose in question, whereby these latter are given better penetrating qualities thanks to the presence of the tall acid products. The new treating oils may also be used in combination with tall pitch, or tall resin acid with or without addition of solvents even in such cases when the pitch or resin acid has previously been subjected to oxidation or cracking. The oil in question may also be used in combination with waxes, paraflin and similar substances.

Our tests have demonstrated that the oil produced from tall resin oil or its fractions by being heated to above 250 C., with a possible addition of metal, e. g. magnesium, in quantities amounting to less than 1 per cent by weight of the oil, either alone or, particularly, in combination with the above described oils derived from tall acid, will yield an excellent result when used as hardening oil for fibre boards.

The oils in question may also be used in combination with so called neutral oil from liquid resin, e, g. produced according to the Swedish Patent No. 98,674, or similar products.

It is also possible to dissolve natural or artificial resins in the oils. Since these, contrary to other generally for board-hardening purposes employed oils, are soluble both in oil-solvents such as turpentine, and in alcohol, the possibilities for a combining with natural and artificial resins, both such of an oil soluble character and those soluble in alcohol, will be considerably increased.

It is a known fact that fibre boards which are 4 hardened with ordinary hardening oils will in the heat treatment receive an uneven surface and not become quite level. These drawbacks are reduced to a very marked degree when using hardening oils according to the invention, probably due to the fact that the penetration of the oils and the subsequent hardening will be effected throughout the entire board. Another quite valuable advantage of the new process is the possibility for applying a thin coating of Bakelite -or other'hardening press-lacquer by means of brushing, spraying or other suitable method on the surface of the hardened board, after which the applied coating may be hardened e. g. by heat-pressing.

The aforementioned heat treatment of the oilimpregnated fibre boards may be effected in the usual way in a heating chamber or else in a hot press.

We claim:

1. In the production of oil-hardened wood fiber boards, the process which comprises impregnating a Wood fiber board with an oily product, comprising a distillate produced by distilling tall oil in a vacuum and collecting the distillate from the commencement of the distillation up to the point at which all of the tall resin oil and at least part of the tall fat acid have distilled oif and the distillate is no longer capable of forming an emulsion with tenfold its Weight of raw linseed oil and double its weight of Water which emulsion is stable for at least 24 hours, then heat treating the so-impregnated board to produce drying and hardening of said distillate and consequent hardening of the board.

2. The process of claim 1 wherein the impregnating oil also contains a fraction distilled from tall oil and selected from a class consisting of tall pitch and tall resin oil.

HILDING OLOF VIDAR BERGSTRM. GUSTAF BRISTOL HEIJMER. KARL GUSTAF TROBECK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

